Apparatus for cutting and hemming bed sheets and the like

ABSTRACT

The application discloses a method and apparatus for cutting bed sheets and the like from a large, continuous length of fabric, forming hems on the cut edges of the fabric panels, and then sewing the hems. The fabric is fed &#34;wrong side out&#34;, and one of the hems is formed upside down while the other is formed right side up. One hem is formed more or less directly above the other. A pair of sewing machines are mounted one above the other, and the entire fabric panel, with the just-formed hem folds, is advanced laterally through the sewing machines, simultaneously sewing both hems. By arranging for the mounting of both sewing machines, one above the other, servicing of the machines by a single operator is readily accomplished. Moreover, the substantial amount of fabric between the two hems is accommodated in a generally vertically oriented loop of the fabric providing for highly efficient utilization of factory space.

BACKGROUND AND SUMMARY OF THE INVENTION

The manufacture of large fabric panels, such as bed sheets, has been arelatively time consuming and expensive operation, involving substantialamounts of manual labor in the forming and sewing of the hems at eachend. In this respect, typically, the fabric utilized in the manufactureof bed sheets, for example, will be woven to a predetermined width, andthe selvage edges of the woven fabric will form the finished edges ofthe bed sheet. The web is cut to predetermined length and hemmed toprovide the finished product. Typically, the hemming operation involvesthe forming of both a large and a small hem at each end, so that the rawcut edges are concealed.

While the forming and sewing of fabric hems by automatic means is a wellknown art, in general, the application of known automatic techniques tothe production of large items, such as bed sheets, has remained ratherelusive. Because of the very large size of the fabric panels, equipmentheretofore proposed for the simultaneous hem folding and sewing of theopposite ends of a bed sheet has proven to be very large and unwieldy,involving not only substantial investment in the equipment, but alsooccupying an unduly large area of valuable factory space. Moreover, thegeometry of such equipment has made it either very difficult orvirtually impossible for a single operator to service sewing machines atopposite sides of the machine, so that additional skilled operatingpersonnel may be required in order to maintain an orderly flow ofproduction. In the past, these practical problems have provensufficiently great that the economics of automatic hem forming andfolding on bed sheets and the like has not been very attractive, and theoperation has been carried out largely by manual processes.

In accordance with the present invention, a unique and entirely novelapproach is taken to the forming and sewing of hems on large panels,such as bed sheets, which enables reliable, consistent, productionoperations to be carried out with equipment which is highly attractiveeconomically, in comparison to present methods. With the apparatus ofthe present invention, the two hems are formed and sewed, one more orless directly above the other, regardless of the length of fabricbetween the hems, and the intervening material is simply gathered in agenerally vertical loop. A pair of sewing machines, one positioned abovethe other, are located laterally adjacent the feeding and foldingsections of the fabric. Once the fabric section is cut to length and thehems are folded, the entire unit is held and laterally transferred in anovel and advantageous manner, to be described, and conveyed past thesewing machines for the sewing operations to take place.

In accordance with one of the more specific aspects of the invention,the fabric is fed generally vertically downward into the hem foldingsection, in a "wrong side out" orientation. The lower hem is foldedupside down, and the upper hem, after severing of the section to length,is folded rightside up. The entire fabric section is then controllablytransferred laterally through the sewing machines.

In accordance with another specific aspect of the invention, a uniqueand simplified arrangement is provided for engaging the fabric afterinitial formation of the hem folds and controllably transferring thefabric laterally, without losing the hem folds. The transfer means bothclamps and laterally advances the fabric, and takes the place of thefeed dogs of the sewing machines, which are rendered inoperative. Inaddition, the transfer means are sufficiently responsive to enable highspeed sewing and back tacking, as is appropriate in a commercialproduction sewing operation.

In accordance with a further specific aspect of the invention, a novelarrangement of fabric supporting and guiding plates is provided whichaccommodates a generally vertically downward, gravity movement of thefabric into precisely measured limit positions to accommodate thenecessary cutting and hem folding operations. Thereafter, selected onesof the guide plates are movable into new positions more appropriate forsupporting of the fabric during the lateral transfer and sewingoperations.

For a more complete understanding of the above and other significantfeatures and advantages of the invention, reference should be made tothe following description of a preferred embodiment of the invention,and to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the apparatus of the invention,shown in condition prior to the start of the feeding, folding and sewingof a large panel, such as a bed sheet.

FIG. 2 is a schematic view, similar to FIG. 1, illustrating the fabricafter feeding into a first limit position in preparation for a hemfolding operation at one end.

FIGS. 3 and 4 are highly enlarged, fragmentary, schematic illustrationsshowing the manner of folding the first hem of the panel.

FIG. 5 is a schematic view, similar to FIG. 1, illustrating the furtherfeeding of the fabric panel after forming of the first hem fold.

FIGS. 6 and 7 are schematic illustrations, similar to FIGS. 3 and 4, butshowing the cutting of the fabric and the folding of the second hem.

FIG. 8 is a schematic view illustrating the position of the sewingmachines and showing certain fabric driving panels of the apparatusreoriented into appropriate positions for the lateral transfer of thesevered and folded web section for the sewing operation.

FIG. 9 is a simplified front elevational view of the apparatus of theinvention showing the positions of the sewing machines and illustratingthe fabric in its initial position, for folding of the hems, and in itsfinal position, after lateral transfer for sewing.

FIG. 10 is an enlarged, fragmentary cross sectional view as takengenerally on line 10--10 of FIG. 9, illustrating details of the fabrictransfer mechanism forming an important feature of the invention.

FIG. 11 is a fragmentary cross sectional view illustrating the dischargeend region of the hem folding plates of the apparatus of the invention,illustrating the manner in which the folded hem is tensioned and sizedimmediately prior to sewing.

FIG. 12 is a top plan view illustrating arrangements for feeding of thefabric in the region of the sewing needle.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Referring now to the drawings, and initially to FIG. 1, the referencenumeral 20 designates a supply roll of fabric web, which may typicallycontain as much as two thousand yards of fabric, for example. In somecases, the fabric 21 on the roll may be folded in half, lengthwise, inwhich case appropriate unfolding equipment (not shown) needs to beincorporated in the overall system. For the purpose of this disclosure,however, it is assumed that the fabric 21 is open width.

The roll 20 typically is supported on a pair of rollers 22, 23, at leastone of which is driven by a motor 24. In order to draw fabric from theroll supply 20, the motor 24 is driven in the appropriate direction andthe fabric 21 is directed into the pan of a scray 25. The scray pan ispivoted at 26 and is yieldably urged to pivot in the upward direction. Asuitable switch 27 is actuated by upward pivoting movement of the scraypan and serves to energize the motor 24 to advance fabric into the pan.When the weight of the fabric in the pan is sufficient to pivot thescray pan downwardly, the switch 27 opens and the motor 24 isde-energized.

From the scray pan 25 the fabric 21 is led over guide rollers 28, 29 andthen over and around a driven feed roller 30 controlled by a motor 31.The feed roller 30 is operated in accordance with the demands of thefeeding, folding, cutting controls on the downstream side of the feedroller. As the feed roller draws fabric from the scray pan 25, reducingthe weight load thereon, the pan eventually lifts sufficiently to tripthe switch 27 and reactivate the infeed drive motor 24. Thus, theenergizing and de-energizing of the drive motors 24, 31 are independent,although of course related.

In the infeed section of the equipment, that is on the upstream side ofthe feed roller 30, provisions are made for precisely aligning the edgesof the fabric 21. To this end, a mechanism of the type shown anddescribed in the Rovin et al. pending U.S. Application Ser. No. 938,335,owned by Automatech Industries Inc., may be employed. Insofar asnecessary or appropriate, the disclosure of that application isincorporated herein by reference. The edge aligning means thereillustrated is in the form of rollers arranged to engage the edgemargins of the fabric at each side, and canted at a slight angle to theaxis of advancement of the fabric. When an edge is detected to havewandered laterally out of its tolerance range, one or the other of thecanted rollers is caused to press upon the fabric as it continues toadvance longitudinally. The canted roller, pressing on the fabric,biases the fabric toward that edge to restore the web to its properalignment, after which pressure on the canted roller is released.

In FIG. 1, the apparatus is shown in the ready condition, prior to thecommencement of a sheet forming operation. In that condition, the cutlower end 32 of the fabric web hangs by gravity from the discharge sideof the feed roll 30. The lower free portion of the fabric is guided andconfined between a pair of vertically disposed upper guide panels 33,34, which extend across the full width of the folding section of themachine, being of sufficient width to accommodate the maximum width offabric web to be processed. At the initiation of a sheet-formingoperation, the motor 31 is energized to drive the feed roller 30 andadvance the fabric. The leading edge of the fabric, under the influenceof gravity, engages a downwardly inclined deflector panel 35, whichguides the fabric downward and forward. Air nozzles 36 may bemomentarily activated during this feeding phase to assist in thedownward and forward deflection of the fabric and to overcome theeffects of friction.

As the fabric reaches the end of the inclined deflector panel 35, itenters a generally vertical guide space 37 (see FIG. 2) defined in partby intermediate front and back guide panels 38, 39 and in part by thelower forward extremity 40 of the deflector panel 35. Downward advancingmovement of the fabric 21 continues until the fabric enters a lowergenerally vertical guide space 41 defined by front and back lower guidepanels 42, 43. At an appropriate location in the lower guide space 41,edge detector means, preferably in the form of a pair of widely spacedphotocells 44, are provided to detect the advance of the edge extremity32 of the fabric web. In the illustrated arrangement, when the photocellbeams are interrupted, the feed motor 31 is de-energized stopping thefeed roll 30 and establishing a reference position for the lower edge 32of the fabric from which hem folding operations may commence. Desirably,control provisions are made for the feed roller 30 to be driven atrelatively high speed (e.g. 36 inches per second) to a level just a fewinches above the photocells 44. At that level, the feed roller 30 isdecelerated to a much slower speed (e.g. 6 inches per second) so thatsubstantial precision may be realized in the final location of the edge32.

To ensure greater precision in the forming and sewing of the lower hem,the photocells 44 are arranged in widely spaced relationship, one moreor less adjacent each side edge of the web. If the leading edge of thefabric is not perfectly horizontal as it approaches the photocell level,the photocell at one side is tripped first, and that energizes asolenoid 44a and causes its plunger 44b to move into clampingrelationship with that side of the fabric. The downward feeding of theweb as a whole continues until the similar photocell at the oppositeside has its beam broken which energizes a similar solenoid and plungerto clamp the web in its opposite edge region. Actuation of the secondsolenoid also serves to stop the feeding roll 30. Although,theoretically, the lower edge of the fabric should at at all times beperfectly square to the horizontal, practical realities are such thatthis may not always occur. Thus, the combination of spaced photocellsand solenoids assures that the hem is properly formed in all cases, eventhough, in some cases, the finished sheet may not be perfectly square.In this respect, the fact that the sheet as a whole may be slightly outof square is not easily detectable and is thus quite tolerable, whereaseven minor misalignments in a relatively narrow hem may be easilynoticeable.

After the leading edge 32 of the web has reached its lower limitposition, the first hem folding operation commences. The folding iscommenced by the front to back, generally horizontal movement of aU-shaped folding bar 45, which is disposed in the region between thebottom edges of the intermediate guide panels 38, 39 and the top edgesof the lower guide panels 42, 43. The folding bar 45 advances from aposition in front of the fabric web 21 to a position well in back of theweb. In so moving, the folding bar picks up the web and carries itrearwardly. Since the upper part of the web is held fixed by the nowmotionless feed roll 30, the lower extremity 32 of the fabric is drawnupwardly, as necessary, to accommodate the rearward horizontal movementof the folding bar.

As reflected in FIGS. 3 and 4, as the folding bar 45 nears its rearwardlimit position, the lower panel 46 thereof passes over the top of ahorizontal folding blade 47, causing the end extremity of the fabric tobe folded upward, horizontally, against the lower panel of the foldingbar. The fabric also rests by gravity upon the horizontal upper panel 48of the folding bar, as indicated in FIGS. 3 and 4. When the folding barhas reached its rearward limit position, a clamping member 49 is broughtdownward against the fabric resting on the upper folding bar panel 48,effectively locking the fabric against the folding bar.

As reflected in the drawings, a small hem folding blade 50 is pivotallymounted at 51, generally in front of the horizontal folding panel 47.When the lower hem folding bar 45 advances in a rearward direction, itpasses over the small hem folding blade 50, drawing the fabric endextremity 32 over the edge 52 of the blade. When the large hem foldingbar 45 has reached its limit position, an end margin of the fabricremains draped over the small hem folding bar, as shown in FIG. 3. Atthis stage, the small hem folding blade is actuated to pivot about itsaxis 51, carrying the end margin of the fabric upward and rearward overthe top of the lower hem folding panel 46, substantially as shown inFIG. 4.

As will be understood, the hem folds thus described include a large hemfold, formed by the fabric section 53, and a small hem fold (oftenreferred to as a tuck-under), formed by the fabric section 54. Ingeneral, and taking into consideration final dimensional adjustmentsincorporated into the procedure and to be hereinafter described, thelength of the large hem section 53 is determined by the horizontalextent of the lower panel 46 of the hem folding bar, and the length ofthe small hem section is determined by the left-over margin of fabricwhich is folded upward and rearward by the pivoting bar 50. Provisionmay be made for forming hems of different size by interchanging of thelarge hem forming bar 45 with other bars having longer or shorter lowerpanels 46, as will be understood. To accommodate such changes in hemwidth, provision is made for vertical adjustment of the position of thephotocell detectors 44, so that the stop position of the fabric edgeextremity 32 may correspond appropriately with the width of the hem tobe formed.

After forming of the lower hem, the folding elements remain in theposition indicated in FIG. 4 during further operations of the equipment,including a further feeding operation to provide a sheet ofpredetermined measured length, and operations necessary to effectfolding of the upper hem. Thus, after completion of the lower hemfolding operation, the feed motor 31 is reactivated to rotate the feedroller 30 and advance the fabric 21 downward through the upper guidepanels. The fabric moves along the deflector panel 35 and then downthrough the intermediate guide panels and down into the guide space 41defined by the panels 42, 43. The guide space 41 is open at the bottom,so that the fabric can collect therein as a loop 55, as required toprovide a fabric section of the desired length. In this respect, controlover the length of the fabric section advantageously is achieved bymeans of an electronic integrator system (not shown), typically ananalog type, associated with the drive motor 31. The controlarrangement, which per se may be more or less conventional, provides forthe summing and integration of pulses proportional to rotationalincrements of the motor 31. After accumulation of a predetermined numberof pulses, the motor is decelerated from its relatively high speed ofadvance to a lower speed, and then stopped altogether, with theaccumulated pulses corresponding rather accurately to a web section ofpreselected length. The condition of the equipment at this stage issubstantially as illustrated in FIG. 5.

Folding and forming of the upper hem, and severing of the web section tolength, is initiated by horizontal movement, in a front to backdirection, of an upper hem folding bar 60, in conjunction with back tofront horizontal motion of a cooperating folding blade 61. In theillustrated form of the invention, and as particularly reflected in FIG.6, for example, the upper hem folding bar 60 advances through thevertical guide plane formed by the upper vertical guide panels 33, 34,so as to deflect the fabric 21 toward the rear. In conjunction, thefolding blade 61 moves from back to front through the guide plane, todeflect the fabric horizontally over the top panel 62 of the folding bar60.

As reflected particularly in FIG. 6, the weight of the hanging fabriccauses the material to be held relatively taut between the lower edge 63of the guide panel 33 and the forwardmost edge 64 of the folding panel61. A small vertical space is provided between the lower edge of theguide panel 33 and the upper surface of the folding blade 61, so that ashort section 65 of the fabric extends downward and forward at an angle.With the folding bar 60 in its rearwardmost position, it is in contactwith a clamping bar 66, which serves to hold the upper margins of thefabric against the folding bar 60. At this stage, the cutting wheel 67traverses the taut, angular fabric section 65, severing a fabric sectionfrom the main supply. The short section of fabric to the left of thecutting knife 67, as shown in FIG. 6, forms the small hem section 68,after downward and rearward pivoting of a small hem folding blade 69,which is mounted on a pivot axis 70. After the initial foldingoperations, the upper hem is in a partially completed condition,substantially as shown in FIG. 7 of the drawing.

In accordance with one of the features of the invention, the deflectorpanel 35 and a similar, downwardly inclined guide panel 71 are pivotallymounted at their upper, rearward edges 72, 73 respectively,accommodating upward pivoting movement of the respective panels intogenerally horizontal positions as illustrated in FIG. 8. The panels 35,71, like the other panels previously described, extend the full width ofthe fabric. Accordingly, when the panels 35, 71 are pivoted upwardly,they carry with them the overlying sections of fabric and bring theminto contact with elongated, transversely disposed transport strips 74,75. The upper deflecting panel 35, in addition to bringing the fabricinto contact with the transport strip 74, also completes the forming ofthe upper large hem, by lifting the fabric up closely adjacent to thelower panel 76 of the upper hem folding bar 60, as clearly reflected inFIG. 8.

In the condition of the system shown in FIG. 8, the fabric is clampedacross its full width by the fabric transport strips 74, 75, pressingagainst the respective panels 35, 71. At this juncture, therefor, therespective fabric hem clamps 49, 66 are released. However, since the hemfold areas of the fabric are isolated from the weight of the fabric bythe transport strips 74, 75, the respective hem folds remain in theiras-folded condition.

As shown in FIG. 8, and in accordance with one of the significantaspects of the invention, the upper and lower hems of the fabric arelocated in generally vertical alignment, one above the other, withsufficient space between to accommodate the presence of the lower of twosewing machines 80, 81.

As reflected in FIG. 9, the location of the sewing machines is laterallyadjacent the fabric 21, after severing thereof from the supply roll andforming of the hems. In FIG. 9, the fabric edges 82, 83 are shown asbeing laterally offset for purposes of illustration only, it beingunderstood that, in actual practice, these edges properly are alignedone directly behind the other.

As reflected in FIG. 9, the pivoting panels 35, 71 extend not only forthe full width of the fabric section, but also for a substantialdistance beyond, sufficient to support the fabric during transferthrough the sewing station and beyond, to an unloading station reflectedby the broken line illustration of the fabric at the left in FIG. 9.Lateral conveyance of the fabric is achieved in accordance with theinvention by means of elongated, ball bearing slide tracks 82a, 83a.FIG. 10 illustrates details of the slide tracks, which may besubstantially identical in construction. There is provided an uppertrack section 84, which extends for the full width of the apparatus,that is, through the feeding and folding position, shown at the right inFIG. 9, across and over full width of the unloading position, shown atthe left in FIG. 9. The upper track 84, which is rigidly mountedhorizontally, is provided with opposed, inwardly opening, generallysemi-cylindrical ball grooves or races 85, 86, in which are contained aplurality of bearing balls 87. A lower track section 88, of a lengthjust slightly greater than the maximum width of a fabric section to behandled in the equipment, is received in the upper track section and hasopposed, outwardly facing, generally semi-cylindrical tracks 89, 90,which cooperatively receive the bearing balls 87.

The upper and lower tracks 84, 88, in cooperation with the bearing balls87, form a lightweight, low friction, horizontal slide mechanism, inwhich the lower track section 88 may be moved laterally from the feedingand folding side to the unloading side, to convey the fabric through thesewing stations. Desirably, the low friction slide arrangement may besubstantially similar in construction to more or less conventionalanti-friction drawer slide arrangements, for simplicity and economy inmanufacture.

As reflected in FIG. 10, there is secured to the lower track or slidemember 88 a bracket 91, which carries at its rearward extemity anelongated gear rack 92. The rack 92 for each slide track cooperates witha drive pinion 93 or 94, suitably located adjacent the sewing machines80, 81 and driven respectively by motors 95, 96. As reflected in FIG. 9,for example, the racks 92 would extendsufficiently far to the left ofthe lower track sections 88 to be able to engage the pinions 93, 94 whenthe tracks 88 are in their right-hand limit positions. When the motors95, 96 are energized, the pinions are rotated to drive the racks 92 tothe left, sufficient to carry the tracks 88 over to left-hand limitpositions reflected by the dotted line position of the fabric 21 in FIG.9.

Secured to the bottom of the lower anti-friction track 88, and extendingalong its full length, are the respective transport strips 74, 75,heretofore mentioned. To advantage, these transport strips may beelongated, narrow sections of a material such as foam-backed pilecarpeting material, for example, with the foam layer 100 being bonded tothe rack supporting bracket 91 and the pile yarns 101 projectingdownward. The upper surface of the supporting panels 35, 71 is, ofcourse, sufficiently smooth to permit free lateral sliding movement ofthe fabric 21 thereover. Accordingly, when the fabric is brought intolight pressure contact with the downwardly projecting pile yarns 101, asreflected in FIG. 10, for example, the fabric is effectively grippedacross its full width and is readily transported laterally withoutslippage or distortion by controlled lateral movements of theanti-friction track 88.

In the procedure of the invention, after forming and folding of theupper and lower hems, the drive motors 95, 96 are activated tocontrollably advance the anti-friction tracks 88 and their respectivetransport strips 74, 75 laterally for sewing of the hems and transportof the finished product to the unloading position. The sewing operationdesirably involves a short back tack, then sewing of the full hem,followed by a finish back tack at the other edge. To this end, thetransport strips 74, 75 are driven to carry the leading edge 102 (seeFIG. 9) of the sheet to and slightly beyond the sewing needles 103, 104,which are desirably aligned in the same vertical plane as viewed fromthe front of the equipment, reflected in FIG. 9. If a one inch back tackis desired, for example, the fabric edge 102 is moved to position oneinch beyond the sewing needles, at which point each sewing machinepresser foot is lowered to its sewing position. The controls for thispurpose may, for example, be a photocell edge detector in conjunctionwith an integrating circuit of generally known type.

Pursuant to the invention, the feed dogs of the sewing machines 80, 81are disabled, so that feeding of the fabric is entirely under thecontrol of the transport strips 74, 75, augmented by auxiliary,synchronized friction wheels 105 associated with each of the sewingmachines and located on the opposite side of the stitch line 106 (seeFIG. 12) from the transport strips. The friction wheels 105 are drivenby separate, variable speed motors 105a, which can be controlled to runsynchronously with, or slightly faster or slower than, the transportstrips 74, 75 for greater control over the sewing operation. Desirably,there are also suitable means (not shown) for varying the pressure ofthe friction wheels on the fabric.

After the fabric is first fed into the starting position, the sewingmachines are activated and the transport drive motors 95, 96 areactivated in reverse, to retract the fabric section 21 (toward the rightin FIG. 9) to form the back tack. The direction of the drive motors 95,96 is thereupon reversed and the fabric is conveyed to the left by thetransport strips, carrying the full width of the fabric section past thesewing station and thus sewing the upper and lower hems across theirfull width. By means of the integrating circuit arrangement and/or bysuitable photocell detectors, the trailing edge 107 of the fabric isdetected as it approaches the vertical plane of the sewing needles 103.When the stitch line reaches the trailing edge extemity 107 of thefabric, the drive motors 95 are automatically reversed in direction toform a short back tack of desired length, whereupon the presser feet ofthe sewing machines are raised and the finished fabric sections areconveyed to the left, to the unloading position shown in broken lines inFIG. 9. During this last mentioned conveying stage, the threads from thesewing machine are either automatically severed to prepare the equipmentfor a further operation. Immediately, a new infeed cycle may becommenced, as will be readily understood.

Preferably, after the sewing operation has been completed, and the websections transported to their left-side limit position, the completedweb sections are automatically gripped, removed and stacked. For thispurpose, the loose draping of the web section permits it to be readilyengaged between the transport strips and by the jaws of a stackingdevice. As soon as the web section is thus engaged, the support panels35, 71 are retracted downwardly, to release the fabric from the grip ofthe transport strips 74, 75.

Pursuant to one aspect of the invention, in the feeding of the fabricand the forming of the hems, fabric is fed with its normally "down" sidefacing to the front of the machine. Its upper hem is then folded "rightside up" while the lower hem is folded "upside down". In addition, bothof the hems are so folded that the main panel of the hem, hereinafterreferred to as the large hem, is narrower than its intended dimension,and the small panel of the hem, hereinafter referred to as the smallhem, is of greater width than is intended. However, during the lateraltransport of the hem-folded fabric to the sewing station, the small andlarge hems are progressively adjusted to the desired size, in a mannerthat maintains the fabric and the hem under a desired degree of tensionand control.

With reference to FIG. 11, for example, there is shown a cross sectionalview of the discharge end extremity of the lower main hem forming panel46 of the folding bar 45 (it being understood that similar arrangementsare provided at the end of the upper hem folding bar 60). Afterpreliminary or initial forming of the hem fold, the large hem panel 53is narrower than desired, while the tuck-under 54 is wider than desired.Then, as the fabric is transported to the left (upward in FIG. 11)toward the sewing station, the fabric enters a transition section 110 ofthe folding panel, wherein the main folding panel 46 increases in widthto a final desired width dimension of the main hem panel. During thistransport phase, the fabric is being held by the transport strips 74,75, so that the increase in width of the main hem panel 53 necessarilyis derived by retracting a portion of the tuck-under 54, whicheventually achieves its final desired width 54' indicated in FIG. 11.

This final hem width adjustment is particularly desirable in the contextof the invention because it maintains a desired degree of tension in thehem panels of the fabric during the lateral feeding phases, immediatelyprior to the passage of the folded hem through the sewing station. Thiscontrolled tension assures that the fabric hem is maintained underproper control until the sewing has taken place. It is understood, ofcourse, that the initial hem folding operation occurs in a section ofthe panel 46 laterally adjacent to the transition section 110, and thatthe illustration of FIG. 11 shows the fabric in a condition in which ithas already been displaced laterally into the transition section.

The apparatus and method of the invention incorporate several highlyadvantageous principles. Truly significant practical advantages arederived from the design of the machine which enables both of the hems tobe formed by a pair of vertically stacked, forwardly facing sewingmachines, which enable a single operator to observe and attend to bothmachines very easily. In addition, the described configuration enablessheet hemming or similar operations to be carried out in greatly reducedamounts of factory space, as compared to previous proposals.

The basic design of the apparatus is such that webs of various width areeasily automatically accommodated. Thus, in general, the apparatus canhandle different width of web by simply readjusting the edge guides andedge detectors, along with appropriate corresponding adjustment in theelectronic controls.

One of the specifically significant mechanical features of the inventionresides in the use of lightweight, anti-friction transport trackarrangements, including relatively conventional anti-friction slidetracks, in conjunction with semi-resilient transport strip materialengageable with the surface of the fabric. An extremely effective suchmaterial is an elongated strip of resiliently backed pile fabric, which,when slightly compressed, is able to effectively grip the fabric,accommodate all of its minor variations, slide freely over the metalsurface of the supporting panels 35 or 71, and reliably advance thefabric. In addition, the arrangement is extremely low inertia, enablinghigh speed advance, and instant reversal of direction of the fabric, ascalled for in carrying out back tacking and sewing operations atconventional industrial sewing speeds.

Desirably, the sewing equipment utilizes automatic bobbin replenishingmechanisms of the type described and claimed in the Rovin U.S. Pat. No.4,117,789, arranged such that each filling of the bobbin is sufficientto enable the sewing of a single hem, and the bobbin is refilled aftereach operation. In this manner, it is possible to use a lock stitchsewing procedure, without concern of running out of bobbin threadpartway through the sewing of a hem and thus producing a defectivearticle. Insofar as is appropriate or necessary, the disclosure of theRovin U.S. Pat. No. 4,117,789, is hereby incorporated by reference.

The process of the invention is uniquely adapted to the high productioncommercial manufacture of large fabric panels, such as bed sheets, whichare required to be hemmed at opposite ends. In a generally simplifiedapparatus, vertically oriented to occupy minimum factory space, fabricis fed downwardly by gravity to a control position, following which thefabric is manipulated in a unique manner along its lower edge margin toform both large hem and small hem folds. Then, after measuring off adesired further length of fabric, the generally continuous length of webmaterial is severed, and the severed end region manipulated to form asecond hem fold. By feeding of the fabric web with the "wrong side"facing forward and then folding the lower hem "upside down" and theupper hem "right side up", it is possible and convenient to constructthe equipment with one sewing machine more or less directly above theother, from which a number of important practical advantages flow.

An advantageous practical feature of the invention resides in theprovision, in conjunction with laterally movable transport strips, ofupwardly movable fabric supporting panels (35, 71) which, after thefabric has been cut and both hems folded, lift the fabric up into lightpressure contact with the transport strips for controlled lateralmovement. This preliminary manipulation of the fabric is carried outwhile the fabric remains clamped at the hem folding bars, but as soon asthe fabric has been engaged by the transport strips, the clamps at thehem folding bars are released, to enable free lateral movement of thefabric relative to the hem folding bars and panels, which are fixedagainst lateral movement.

The design of the equipment accommodates working parts of low mass andinertia, such that the power and energy requirements for operation ofthe equipment are extremely low. For example, in a typical commercialapparatus for the automatic hemming of bed sheets, the total powerrequirements are approximately two horsepower, of which approximatelyone and a half horsepower is related to the sewing machines themselves.

It should be understood, of course, that the specific form of theinvention herein illustrated and described is intended to berepresentative only, as certain changes may be made therein withoutdeparting from the clear teachings of the disclosure. Accordingly,reference should be made to the following appended claims in determiningthe full scope of the invention.

I claim:
 1. Apparatus for forming and sewing hemmed bed sheets or thelike, which comprises,(a) a supply of web material, (b) a feed roll forcontrollably advancing said web material, (c) guide means for receivingthe advanced material by gravity, (d) control means operative tointerrupt the advance of fabric when the leading edge reaches apredetermined location, (e) means for forming and folding a hem acrossthe full width of the material, (f) means for gripping the material inthe region of the thus formed hem and transporting the materiallaterally, (g) means for sewing the hem during the lateral transport ofsaid material.
 2. Apparatus according to claim 1, further characterizedby(a) said hem forming means being generally stationary and said webmaterial being transported laterally relative thereto, (b) said hemforming means including means for forming large and small hems at saidleading edge, and (c) said hem forming means including means forexpanding the width of said large hem progressively as said web materialis transported toward said sewing means.
 3. Apparatus according to claim1, further characterized by(a) a pair of widely spaced sensors fordetecting the downwardly moving leading edge of said web material, (b)separate, widely spaced clamp means for engaging said web material uponsensing of said leading edge by an associated sensor, and (c) hemforming and folding means located between said sensors and said clampmeans.
 4. Apparatus according to claim 1, further characterized by(a)means for further advancing said web material to form a web section ofpredetermined overall length, (b) means for severing said web section tosaid predetermined length, (c) means for forming and folding a secondhem across the full width of said web material, (d) second sewing meanslocated generally above the first mentioned sewing means, whereby saidhems may be sewed simultaneously one above the other.
 5. Apparatusaccording to claim 4, further characterized by(a) said hem folding meanscomprising means for forming one of said hems right side up and theother of said hems upside down.
 6. Apparatus according to claim 1,further characterized by(a) said transport means comprising alight-weight, low-friction, elongated slide member engageable with theweb material across its full width adjacent said hem, and (b) means forcontrollably moving said slide to carry said web material past saidsewing machine while substantially maintaining the integrity of thefolded hem.
 7. Apparatus according to claim 6, further characterizedby(a) a panel cooperable with said slide for slideably supporting webmaterial engaged by said slide.
 8. Apparatus according to claim 7,further characterized by(a) said panel being controllably movable intocooperable relation with said slide.
 9. Apparatus according to claim 8,further characterized by(a) said panel being pivotally mounted andhaving a first, downwardly inclined position spaced from said slide andenabling said panel to guide and deflect downwardly moving web material,and an elevated position, slideably supporting said web material inpressure contact with said slide.
 10. Apparatus according to claim 1,further characterized by said means for gripping and transportingcomprising(a) elongated transport members engaging the materialeffectively substantially continuously over its full width on one sideof the stitch lines to be formed during sewing, (b) separate drive meansengaging the material on the opposite sides of said stitch lines, and(c) means for controllably varying the drive speeds of said transportmembers and said separate drive means, one with respect to the other.